(image: impnerd.com)

One of the big challenges with solar energy is trying to figure out how to store it for use on days when there’s not much sun. But a California start-up says that they’ve figured how to store sunlight—they’ll use salt, reports MSNBC. SolarReserve, based in Santa Monica, CA, is planning to build a new solar plant outside of Tonopah, Nevada, where they will be using molten salt to store the sun’s energy.

Salt can store heat quite efficiently, and the heat retention lasts for a long period of time, says Nevada’s Energy Director of Renewable Energy Procurement, David Hicks.

“So once you heat that salt up, it loses that heat content on a very slow basis, Hicks explains. “It doesn’t lose it quickly so it allows you time to shift that energy.”

The heat retention will last even on a partly cloudy day, he says, and confirms that the salt technology will work. A photovoltaic panel, on the other hand, will lose 80 percent of its power output when a cloud passes over it.

Like many solar-thermal systems, SolarReserve uses a field of mirrors, or heliostats, to focus the sun’s heat on a tower to heat liquid—in this case, molten salt—to power a turbine.

SolarReserve is planning to start construction next year, though the Nevada Public Utilities Commission must still approve it. The company claims that this project will supply power to 75,000 homes.